Tungsten

tungsten

yttrialite-(Y)

phengite

siderite

Formula: W
Native element
Crystal System: Isometric
Specific gravity: 19.226 calculated
Hardness: 7.5 mohs
Streak: Grey
Colour: Silver-white to steel-grey
Melting point: 3,422^oC, the highest melting point of all metals (ChC).
Boiling point: 5,550^oC
Abundance in the Earth’s crust: 1.25 parts per million by mass, 0.1 parts per million by moles
Abundance in the Solar System: 4 parts per billion by mass, 30 part per trillion by moles
Environments

Placer deposits
Hydrothermal environments

Tungsten has been extracted from its ore for many years, and thought not to exist in the native state, but in 2011 it was approved as a mineral species, after being found at the type locality as a native element. When present in compounds, tungsten exists mostly in the oxidation state VI, as W⁶⁺ (ChC).

Localities

At the type locality, the Bolshaya Polya River, Khanty-Mansi Autonomous Okrug, Russia, native tungsten has been found in gold placers, occurring as polycrystalline grains and masses, and rarely as cubo-octahedra, associated with yttrialite-(Y), quartz, phengite and siderite (MM 85.1.76-81, HOM).

At the Rai-Iz Ophiolite Massif, Tyumen Oblast, Russia, native tungsten has been found in heavy concentrates from crushed quartz (HOM), and in quartz veins in the Mt Neroyka rock-crystal field, Ust–Puiva, Tyumenskaya Oblast, Russia (MM 85.1.76-81, HOM).

Tungsten-bearing minerals include:

Sulphides - the sulphide anion is S^2-
Oxides - the oxide anion is O^2-
Chlorides - the chloride anion is Cl^-
Tungstates - the tungstate anion is (WO⁶⁺O₄)^2-
Nesosilicates - insular (Si⁴⁺O₄)^4- groups

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